The invention relates to a brush seal for sealing an annular gap between a rotor/stator arrangement, and to a method for manufacturing such a brush seal.
The brush seals are mounted in a stator housing surrounding a rotor concentrically, with the bristles fitting together closely and being arranged at an angle to the radius. The ends of the bristles touch the rotor at its circumference, or end shortly before, so that they provide a seal between chambers which are subjected to different pressures on both sides of the seal under all operating conditions. Because of their elasticity and their angular position relative to the rotors, the bristles can bend to compensate for eccentricities of the rotor and/or shaft and for rotor imbalance.
A brush seal of the generic type is disclosed in German patent document DE-OS 39 07 614. However, because the bristles are wrapped around a rotor-concentric clamping ring and surrounded by a C-shaped clamping ring, diagonal alignment of the bristles relative to the rotor is not possible, especially at larger angles, and the bristles cannot maintain a given diagonal angular pitch during operation. In addition, stronger clamping of the bristles, especially in the case of ceramic fibers, is not possible since high pressure at the edge causes premature wear or breakage of the bristles. This is especially true with regard to the desirable use of very fine and/or extremely thin bristles.
The object of the invention, therefore, is to provide a brush seal that permits diagonal positioning of the bristles relative to the rotor and ensures the functional reliability of the brush seal while maintaining the angular pitch of the bristles over the entire operating range. A method is also provided for simple manufacture of the core ring of such a brush seal.
These and other objects and advantages are achieved according to the invention by using a plurality of separating disks spaced apart from one another at an angular pitch .alpha., so that a uniform diagonal angular pitch is assumed over the entire circumference of the brush seals. The bristle bundles thus aligned by the separating disks each surround a winding rib which is located between the separating disks and also connects adjacent separating disks with one another. Together with the clamping force exerted by the clamping ring, it is possible to secure the bristle bundle reliably at the predetermined angular orientation.
One advantage of the invention is that by using separating disks mounted at an angle in the interior of the clamping ring, the bristle bundles are forcibly aligned at an angle .beta. relative to the circumference of the rotor without extreme clamping force being required to hold the bristle bundles.
Another advantage of the invention is that by using a straight blank (for example a wire) the core ring, consisting of separating disks and winding ribs arranged alternately, can be manufactured in an economical fashion by sawing or milling. When a disk milling cutter is used, whose disk thickness corresponds to the distance between two adjacent separating disks, it cuts circumferential grooves in the wire as it makes a pass in a circular movement around the wire so that a winding rib of the desired diameter remains between two adjacent separating disks. The position of the axis of the disk milling cutter relative to the lengthwise axis of the wire, at an angle that corresponds to the angular pitch of the separating disks relative to the radius, permits a diagonal orientation of the separating disks relative to the axis of the core ring as well as an elliptical shape of the separating disks.
After each pass, the wire is advanced by the constant distance between the separating disks in the clamp, so that the separating disks together with the winding ribs are gradually cut from the wire. When the wire has been machined over its entire length, it is bent into a core ring and joined. The finished core ring can then be provided with the bristles and placed in the clamping ring. Final machining to produce a brush seal then follows .